ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM Tropical Depression Seven-E Discussion Number 1 NWS National Hurricane Center Miami FL EP072021 900 AM MDT Sat Jul 17 2021 The broad low pressure system that the NHC has been monitoring for the past few days well offshore the southwestern coast of Mexico has finally developed enough organized deep convection and a well-defined inner-core wind field to be classified as a tropical depression. The initial intensity is estimated to be 30 kt, which is a little below the consensus T2.5/35-kt classifications from TAFB and SAB. The initial motion estimate is an uncertain 295/15 kt due to the lack of a well-defined center prior to 1200 UTC. Regardless, the global and regional models are in exceptionally good agreement on the cyclone moving west-northwestward today, and then turning toward the west by late tonight or early Sunday, with that general motion continuing through 72 hours. Thereafter, the deep-layer subtropical ridge to the north that will steer the system for the next 5 days is expected to build slightly southward, nudging the cyclone on a west-southwestward track at 96 and 120 hours. The NHC forecast track lies close to but a little slower than the various consensus models out of respect for the slower GFS and GFS-ensemble models, which are forecasting a stronger and, thus, more vertically deep tropical cyclone that should move slower compared to the other weaker models. During the next 48 hours or so, the cyclone is expected to remain embedded within an environment conducive for strengthening, characterized by light wind shear (<10 kt), sea-surface temperatures (SST) above 27 deg C, and deep moisture through the low- to mid-levels of the troposphere. Furthermore, a large upper-level low located just west of the Baja California peninsula, which has been enhancing the poleward outflows of this disturbance and Hurricane Felicia farther to the west, is forecast to persist for at least the next couple of days. All of these favorable conditions argue for at least modest strengthening during that time, with the only hindering factor being the large size of the system's circulation. Thereafter, the cyclone will move over sub-26C SSTs, which should act to cap the intensification process despite the low vertical wind shear conditions that are expected to persist. However, the rate of weakening is forecast to be a little slower than normal due to the southern half of the circulation remaining over warmer waters, which will provide warm moist inflow to help fuel thunderstorms near the inner-core. The NHC intensity forecast closely follows the NOAA-HCCA consensus model through 60 hours, and then is a little above all of the consensus models thereafter. FORECAST POSITIONS AND MAX WINDS INIT 17/1500Z 16.8N 109.2W 30 KT 35 MPH 12H 18/0000Z 17.3N 110.8W 40 KT 45 MPH 24H 18/1200Z 17.9N 112.8W 45 KT 50 MPH 36H 19/0000Z 18.2N 115.1W 50 KT 60 MPH 48H 19/1200Z 18.3N 117.5W 55 KT 65 MPH 60H 20/0000Z 18.5N 120.0W 55 KT 65 MPH 72H 20/1200Z 18.5N 122.6W 50 KT 60 MPH 96H 21/1200Z 18.2N 127.7W 40 KT 45 MPH 120H 22/1200Z 17.9N 132.9W 35 KT 40 MPH $$ Forecaster Stewart NNNN